This invention relates to a process for obtaining an oxygen enriched gas from a mixed gas containing principally oxygen and nitrogen as gas components, such as air, by means of pressure swing adsorption (PSA).
Pressure swing adsorption systems and process have been widely used to produce oxygen enriched streams from mixed gases, including air, and a multitude of such systems and processes have been utilized.
It is advantageous, in such systems, to utilize a relatively short time cycle for carrying out the process inasmuch as shorter times obtain good utilization of the sieve material used to adsorb one of the components. The short cycle times generally employ a finer particle size of sieve material to reduce diffusive resistance. Typical examples of short cycle times are shown and described in U.S. Pat. Nos. 4,194,891 and 4,194,892. Oxygen production increased with the process in the aforementioned patents however the yield was fairly low, e.g., 10-20% yields.
Conventional vacuum PSA processes do produce a higher oxygen yield (50-60%) however the production rate is somewhat low. The normal production rate of conventional three bed PSA processes is not particularly high; as an example, typically, the bed size factor is about 2000-2600 kg of zeolite per metric ton of oxygen produced per day.
Optimally, one would obviously like to obtain the high production rate typified by faster cycle times and finer sieve particles along with the high yield typlified by conventional three bed systems yet have a process that is inexpensive and relatively simple in operation.